In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Allaah (The Most High) said:
قُلۡ أَرَءَيۡتُمۡ إِن جَعَلَ ٱللَّهُ عَلَيۡڪُمُ ٱلَّيۡلَ سَرۡمَدًا إِلَىٰ يَوۡمِ ٱلۡقِيَـٰمَةِ مَنۡ إِلَـٰهٌ غَيۡرُ ٱللَّهِ يَأۡتِيڪُم بِضِيَآءٍۖ أَفَلَا تَسۡمَعُونَ
قُلۡ أَرَءَيۡتُمۡ إِن جَعَلَ ٱللَّهُ عَلَيۡڪُمُ ٱلنَّہَارَ سَرۡمَدًا إِلَىٰ يَوۡمِ ٱلۡقِيَـٰمَةِ مَنۡ إِلَـٰهٌ غَيۡرُ ٱللَّهِ يَأۡتِيڪُم بِلَيۡلٍ۬ تَسۡكُنُونَ فِيهِۖ أَفَلَا تُبۡصِرُونَ
وَمِن رَّحۡمَتِهِۦ جَعَلَ لَكُمُ ٱلَّيۡلَ وَٱلنَّهَارَ لِتَسۡكُنُواْ فِيهِ وَلِتَبۡتَغُواْ مِن فَضۡلِهِۦ وَلَعَلَّكُمۡ تَشۡكُرُونَ
Say (O Muhammad ): “Tell me! If Allah made night continuous for you till the Day of Resurrection, who is an ilah (a god) besides Allah who could bring you light? Will you not then hear?”
Say (O Muhammad ): “Tell me! If Allah made day continuous for you till the Day of Resurrection, who is an ilah (a god) besides Allah who could bring you night wherein you rest? Will you not then see?”
It is out of His Mercy that He has put for you night and day, that you may rest therein (i.e. during the night) and that you may seek of His Bounty (i.e. during the day), and in order that you may be grateful.
Few Reminders From The Above Aayaat
The (night and day) are a bestowal from Allaah to His servants and this should make them thankful to Allaah, worship Him alone and fulfil His Rights. Allaah- out of His Mercy- created the day for them in order that they may seek after His Bounties- seeking after their provisions and livelihoods during daylight. And Allaah created the night for them (as as means of) rest and repose- (allowing) their bodies and souls to take a rest due to tiredness from work during the day. This is a bounty of Allaah (bestowed) on His servants and Mercy (from Him). Is there anyone who is able to do this (besides Allaah)?
And regarding the night (i.e. after Allaah made it known that He was the one who appointed the night for them), He said: [أَفَلَا تَسْمَعُونَ -Then will you not then hear]; and regarding the day (i.e. after Allaah made it known that He was the one who appointed the day for them), He said: [أَفَلَا تُبْصِرُونَ – Then will you not then see?]; this is because the (faculty) of hearing is sharper than the (faculty) of sight during night time, and the (faculty) of sight is sharper than the (faculty) of hearing during day time.
In these Aayaat (i.e. Al-Qasas 71, 72 & 73) the servant is exhorted to ponder upon the blessings Allaah has bestowed on him (or her). He (or she) should contemplate (upon what the state of affairs would have been) if such blessings were absent, for if a servant were to contemplate (upon the state of affairs due to) the presence (of such blessings) compared (to what the state of affairs would have been if such blessings were) absent, he (or she) will realise the (great) position of this favour; as opposed to the one who merely goes along with the normal state of affairs and considers (these favours) as something that will neither cease to carry on nor come to an end. So his (or her) heart is hindered from praising Allaah for these blessings and from realising that he (or she) is in need of Allaah every time. This (state of affairs) neither prompts his (or her) thoughts towards thanksgiving nor remembrance.
[Source: Tayseer Al-Kareem Ar-Rahmaan Fee Tafseer Kalaam Al-Mannaan’. Publisher: Daar Ibn Hazm 1st Ed. 1424AH (Year 2003). Paraphrased & Abridged]